First of all--BDAG does not list all of the vocabulary necessary for Koine. There are tens-of-thousands of words not in BDAG that will show up in Josephus, Philo, Plutarch, Epictetus, Dio Chrysostom, Pausanius, Lucian, Galen, Philostratus, καὶ τὰ λοιπά.

On the other hand, not everything in LSJM was on the lips of the audiences of Paul and Luke as they traveled around. Welcome to the world of dysfunctional Greek studies.

One should add that "meaning" of a word in any language is not just its definition but its relationship to other words that could have been chosen, potentially. Thus, if one does not know the choices available, one does not really understand or grasp a particular word. And no, Louw-Nida "Semantic Domain" does NOT provide that perspective, since they only list the relatively small selection of NT vocab items. People reading German or French and with access to monolingual dictionaries, or even to two-way glossaries, are better off in that regard than people reading NT and early Christian literature.

If yes, would you say that LSJ is on the same level of authority as, say, BDAG?

LSJ is used out of desperation. It is fossil evidence from classical philology a dinosaur which went out of existence along with "western civilization."

Read The Secret History by Donna Tartt.

I'm not sure what a work of fiction has to say about 19th century lexicography. In fact, the LSJ still provides a huge amount of useful information. Does it need updating? Certainly. Could it use an injection of modern language theory, a dash or two of updated etymological information, and a pinch of documents discovered even since the supplement went to print? Of course, but it's still a magnificent dish nonetheless.

Got it. Thank you all. What throws me off is that I have read where some grammarians have bemoaned the state of LSJ, such as the quote below:

No one has drawn more attention to the methodological issues and, well, let’s face it, flaws, in our New Testament Greek lexicons than John A. L. Lee. In a good summary statement of the state of affairs for our lexicons, Lee says, “The concise, seemingly authoritative statement of meaning can, and often does, conceal many sins — indecision, compromise, imperfect knowledge, guesswork, and, above all, dependence on predecessors.”

Some may be gratified to note that New Testament lexicons are not the only targets of Lee’s critique. Regarding the standard lexicon for Ancient Greek — Liddell-Scott-Jones — Lee is unreserved: it “has no coherent definition method, but relies on glosses; its basic material is derived from predecessors, in some cases descending from the ancient lexicographers; and the organization is chaotic as a result of piecemeal revisions.” (Advances in the Study of Greek; Constantine Campbell)

Got it. Thank you all. What throws me off is that I have read where some grammarians have bemoaned the state of LSJ, such as the quote below:

No one has drawn more attention to the methodological issues and, well, let’s face it, flaws, in our New Testament Greek lexicons than John A. L. Lee. In a good summary statement of the state of affairs for our lexicons, Lee says, “The concise, seemingly authoritative statement of meaning can, and often does, conceal many sins — indecision, compromise, imperfect knowledge, guesswork, and, above all, dependence on predecessors.”

Some may be gratified to note that New Testament lexicons are not the only targets of Lee’s critique. Regarding the standard lexicon for Ancient Greek — Liddell-Scott-Jones — Lee is unreserved: it “has no coherent definition method, but relies on glosses; its basic material is derived from predecessors, in some cases descending from the ancient lexicographers; and the organization is chaotic as a result of piecemeal revisions.” (Advances in the Study of Greek; Constantine Campbell)

Lee's assessment has some truth in it, but LSJ is still indispensible if you want to read anything outside of the NT. Any lexicon should function as the starting point, and not the final word. Ha. I'm funny.